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How-To Geek

Ubuntu 11.04 is finally here and you can’t wait to download it, but as is typical on any Ubuntu release day, the mirrors are crawling. Luckily if you have an old Ubuntu .iso you can update it easily with zsync.

Zsync is a Linux command that allows you to compare an existing .iso with an up-to-date zsync meta file to download only the missing or out of date parts. Combine those parts with your existing file and what you are left with is a completely up to date iso without spending the time to download the entire file.

Just how much bandwidth can this save? In our testing, upgrading an iso from Ubuntu 10.04.2 to 11.04 Beta 2 needed to download about 89% of the original file and 10.10 to 11.04 Beta 2 needed 84%. Obviously the more current the original file is, the less you will need to download.

Install zsync

While you are installing Cygwin you will want to make sure you search for zsync on the select packages step.

Zsync is available in the universe repo all the way back to Karmic Koala. So if you are currently using Ubuntu you can install zsync with the normal apt-get command.

sudo apt-get install zsync

Update ISO image

To update your old Ubuntu .iso image, open a command prompt and issue the following command with similar options.

zsync -i /path/to/old/ubuntu.iso http://Path-to-Ubuntu.iso.zsync

This will compare your existing file with the new iso available online, download the missing parts from your current iso, and give you a fully up-to-date new file. Here is an example that lets us update our Ubuntu 10.04.2 image to the latest Ubuntu 11.04.

Note: Using the below command will keep your original Ubuntu 10.04.2 .iso in tact and will create a new Ubuntu 11.04 .iso file.

This method of downloading Natty Narwhal would’ve saved me lots of time and bytes but the Ubuntu servers must be under very heavy stress coz I’m getting an error. It can’t connect. :( Too bad. I guess the old torrent way is the only thing reliable for now.

I had no problem downloading Natty Narwhal today. I’m going to install it via bootable USB stick onto an Inspiron Mini 10 netbook that I have. It’s running XP Home now, but I would like to start experimenting with Linux. It seems like a good candidate for the switch because this particular model originally came with the option of Ubuntu factory installed.

Hi i tried to use this method but it did not work can you help here is what happened in the terminal
nyumbani@mohamed-nyumbani:~$ zsync -i ‘/home/nyumbani/Downloads/ubuntu-10.10-desktop-amd64.iso’ http://releases.ubuntu.com/nat……iso.zsync
#################### 100.0% 22.7 kBps DONE